1. Field of the Invention
The invention is directed to a process for producing a cylinder with at least one outward bulge extending along its length and with a base made of steel for a piston-cylinder unit.
2. Discussion of the Prior Art
In modern mines, especially in coal mines, a self-advancing support is used in fully mechanized operation. The self-advancing support which supports the hanging roof has at least two hydraulic cylinders or, depending on the size, even four hydraulic cylinders. Problems occurred in the past in arranging the external hydraulic lines at the hydraulic cylinders because the external hydraulic lines were constantly damaged or even destroyed under the rough operating conditions. For this reason, cylinders with bulges were developed, wherein hydraulic ducts were accommodated in the outwardly extending bulge, so that these hydraulic ducts were protected from falling rock. Prior known production of cylinders of this type start with a forged piece which is mechanically machined on all sides. The base is produced separately and connected with the cylindrical part. This known process has to be considered unfavorable with respect to consumption numbers and cycle time.